1. Field of the Invention
The present invention relates to apparatus for generating free radical species and particularly to hydroxyl free radical generators and methods of use in water treatment facilities.
2. Description of Related Art
The use of aquatic systems for use by the general public, for example, swimming pools, spas, hot tubs, decorative fountains, cooling towers and the like, has led to a variety of water quality problems. For instance, improper chemical balances in the water can lead to various types of contamination including bacterial and viral contamination. To address such problems, pool operators have turned to the use of chemical sanitizers as a typical water sanitation method. Halogen donor compounds, such as chlorine or bromine can be effective sanitizers so long as they are maintained at well-defined and constantly controlled concentration levels in the water. It is important that the concentration of these chemical sanitizers is not allowed to become too high and possibly cause irritation to the users and damage to the water system. Insufficient sanitizers may result in a contaminated condition. Other systems have been developed. For example, Ruffin in U.S. Pat. No. 3,079,498 discloses a swimming pool water purifier that provides germicidal ultra-violet radiation to a stream from and to the swimming pool.
Other efforts aimed at sanitization or treating aquatic systems have been disclosed. For example, Czulak et al., in U.S. Pat. No. 3,336,099, disclose an apparatus for the sanitization of liquids with special application to water storages and swimming pools by passing such a liquid from the swimming pool around an ultraviolet radiation source to expose the liquid to said radiation. Koubek, in U.S. Pat. No. 4,012,321, discloses oxidation of refractory organics in aqueous waste streams by hydrogen peroxide and ultraviolet light by introducing the liquid to be treated in a photolysis chamber, to expose the liquid to the ultraviolet light. Pisani, in U.S. Pat. No. 4,906,387, discloses a method for removing oxidizable contaminants in cooling water used in conjunction with a cooling tower by including means for removing a portion of the recirculating water which passes through the cooling tower to create a slipstream of water to be treated and treating the slipstream water with chemicals to provide a hydroxyl free radical into the water to enhance oxidation, inducing cavitation in the slipstream water, then irradiating the slipstream water with ultraviolet radiation to thereby cause the oxidizable contaminants to be oxidized and therefore removed before the slipstream water is reintroduced back into the cooling tower. Cater et al., in U.S. Pat. No. 5,043,080, disclose treating contaminated effluents and ground waters wherein the liquid effluent or ground water containing the organic contaminants is contacted with hydrogen peroxide and transition metal ions; the hydrogen peroxide and transition metal ions are present in effective amounts based on the concentration of the organic contaminants in the liquid and the liquid effluent is then irradiated with ultraviolet light to decompose the organic contaminants. Weres et al., in U.S. Pat. No. 5,439,577, disclose an electrochemical device for generating hydroxyl free radicals in the treated water using a novel electrode which is capable of operation at sufficiently positive anodic potential to produce the hydroxyl radicals in the treated water.